#include <stdio.h>

#define ROWS 3
#define COLS 4

int sum2d(int rows, int cols, int ar[rows][cols]);

int main() {
    int i, j;
    int rs = 3;
    int cs = 10;
    int junk[ROWS][COLS] = {
            {2,  4,  6, 8},
            {3,  5,  7, 9},
            {12, 10, 8, 6}
    };
    int morejunk[ROWS - 1][COLS + 2] = {
            {20, 30, 40, 50, 60, 70},
            {5,  6,  7,  8,  9,  10}

    };
    int varr[rs][cs]; //变长数组

    for (int i = 0; i < rs; ++i) {
        for (int j = 0; j < cs; ++j) {
            varr[i][j] = i * j + j;
        }
    }
    printf("3x5 array\n");
    printf("Sum of all elements = %d\n", sum2d(ROWS, COLS, junk));

    printf("2x6 array\n");
    printf("Sum of all elements =%d\n", sum2d(ROWS - 1, COLS + 2, morejunk));

    printf("3x10\n");
    printf("Sum of all elements = %d\n", sum2d(rs, cs, varr));
    return 0;
}

int sum2d(int rows, int cols, int ar[rows][cols]) {
    int r;
    int c;
    int tot=0;

    for (r = 0; r < rows; r++)
        for (c = 0; c < cols; c++)
            tot += ar[r][c];
    return tot;
}
